"Not trick-or-treating is just not an option for us. It would devastate him," says Amanda Higgins-Lekebusch, mother of 7-year old Owen, who is anaphylactic to peanuts. "He doesn't get to eat any of the candies, I have safe candy for him and he's fine with that. It's more just the ritual of going to the doors and ringing the doorbell."

"You tell your child early on, listen you're not going to eat that. Why don't we gather those items and donate them to a homeless shelter, a food bank. Look at it as collecting money for UNICEF. So don't make it all about the candy, make it about the sprit as well."

Bast, who has been on a gluten-free diet for 16 years, recalls NFCA's inaugural event, which was incidentally held on Halloween.

"We had a coffin outside a person's house and her son popped out of the coffin with a loaf of bread, and there was a skeleton that said 'I waited too long for my diagnosis,' and a vampire crying, 'I want to test your blood,' and we made people feel like, yes you can do this," said Bast.

"It's well-known that egg and cow milk allergy is often outgrown, but it may take up to the age of 15 years to do that. Peanut allergy as well has been established to be outgrown, maybe 20 percent of children do this," said Assad.

Adults, however, are unlikely to outgrow their allergies and are more sensitive to shellfish and tree nuts than some of the other eight allergens.